News Release

New Cosumnes River research partnership announced

Peer-Reviewed Publication

University of California - Davis

On Northern California's Cosumnes River, the only remaining waterway flowing unchecked from the Sierra Nevada to the Sacramento River Delta, a new research project is beginning that is likely to become a model for future river management and restoration across the nation.

The Cosumnes Research Group is the outgrowth of a long-standing collaborative relationship between UC Davis scientists and The Nature Conservancy, which operates the Cosumnes River Preserve and is its largest landowner.

Start-up funds of $1.5 million have been provided by the CALFED Ecosystem Restoration Program and $500,000 by the David and Lucile Packard Foundation Conservation Program. Participants in the research program include the state, federal and private partners in the Cosumnes River Preserve, the East Bay Metropolitan Utility District and local landowners.

"In this new project, the Cosumnes watershed will serve as an extraordinary natural laboratory and classroom," said Jeffrey Mount, chair of geology at UC Davis and director of the UC Davis Watershed Center. "The river has an active floodplain and no dams, making it ideal for studying the relationship between the hydrologic cycle and the plant, animal and human communities that live in the watershed. What we learn here will have implications for how we manage our relationship with all of the rivers of the Great Central Valley."

The work of the Cosumnes Research Group is of critical importance in guiding the preserve's management and restoration activities, said Mike Eaton, director of The Nature Conservancy's Cosumnes River/Delta Project. "We expect this program to become a model for collaboration elsewhere. We also recognize the tremendous research values of these lands and encourage learning on location’ at all age levels."

Since its first purchase of a 100-acre grove of valley oaks on the Cosumnes River in 1984, The Nature Conservancy has secured permanent protection for nearly 40,000 acres in the floodplains of the Cosumnes and Mokelumne rivers.

The new Cosumnes Research Group has four main goals:

  • to conduct baseline scientific surveys;
  • to design and implement long-term hydrologic, biologic and land-use monitoring programs;
  • to develop new methods to measure the success or failure of conservation programs in the watershed;
  • to use the lessons learned to guide river and floodplain restoration programs throughout the Central Valley.

The Cosumnes (pronounced Kuh-SOOM-ness) River begins in the steep, forested canyons of the Sierra between U.S. Highway 50 and State Road 88. After its three forks join in the foothills, the river emerges onto the floor of the Central Valley west of State Road 16.

The rich soils of the Cosumnes floodplain support highly productive farms, cattle ranches and vineyards. Much of the riverbank has been built up with low levees, but the Cosumnes is still prone to spilling over its banks and flooding surrounding fields. Despite the well-known flood threat, there is growing pressure to build residential developments along the river and on the floodplain.

Just east of Interstate 5, the Cosumnes joins the Mokelumne River and flows to the Sacramento River Delta.

The Cosumnes and its surrounding lands are home to a rich variety of animals and plants. Vernal pools and "lagunitas" that form on the floodplain contain rare plants and endangered fairy shrimp. More than 200 species of birds, including the Swainson's hawk, which is on the state list of threatened species, and geese, ducks, warblers and sandhill cranes reside in the floodplain forests, marshes and farm fields.

In riverside forests, beavers harvest branches from tall cottonwood trees and scrub jays gather acorns from rare old groves of valley oaks. The river and its surrounding floodplains support dozens of kinds of native fish, including the endangered chinook salmon and the Sacramento splittail, which is a candidate for the federal endangered species list.

One of the most interesting experiments already under way in the watershed was begun in 1995, when Nature Conservancy scientists began breaching riverside levees along the Cosumnes. Since December 1995, the river has "flooded" through two 100-foot-long gaps and meandered through the adjacent field in a path similar to its original course before the levees were built.

Juvenile salmon and native Delta fish have been observed using the flooded areas to feed and grow, and splittail have used the native vegetation to lay their eggs in the shallow waters. The floodwaters deposited nutrient-rich sand and soil in the field, creating a natural seedbed. After the water receded, a young forest of cottonwood and willow sprang up almost immediately.

The 100-acre field now grows chest-high cottonwoods, willows and other native vegetation.

The public can visit the Cosumnes ecosystem at the Cosumnes River Preserve. Information about the preserve is available online at http://www.cosumnes.org or by telephone at (916) 684-2816.

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Media contacts:

-- Sylvia Wright, News Service, (530) 752-7704, swright@ucdavis.edu
-- Jeff Mount, Geology, (530) 752-7092, mount@geology.ucdavis.edu
-- Mike Eaton, Cosumnes River Preserve, (916) 683-1699, meaton@cosumnes.org


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